Interior permanent magnet (IPM) rotors using various rotor types are known in the art. For example, in one prior art design as shown in U.S. Pat. No. 5,701,064, a rotor has teeth which form a discontinuous, non-contiguous outer surface contour. Although such designs are useful, there is a need for rotor which provides a more constant power over a wider speed range. In addition, there is a need for a motor having a rotor which provides properties which are properly balanced.